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Original question:

AM6442: gpio_input_interrupt AM64

AM6442: DTS changes to run GPIO_INPUT_INTERRUPT example from Linux

Mateusz Szalkowski
Prodigy 130 points
Part Number: AM6442

Hello,

I'm trying to run a modified GPIO_INPUT_INTERRUPT example from MCU SDK using R19 gpio for interrupt. I had to deal with SCIClient error:

[Error] Sciclient event config failed!!!
ASSERT: 0.334s: syscfg/ti_drivers_config.c:Sciclient_gpioIrqSet:116: FALSE failed !!!

To solve this issue I did a few things:

  • changed sciclient_defaultBoardcfg_rm.c according to this tutorial
  • rebuilt bootloaders with similar changes in rm-cfg.c and sysfw_img_cfg.h in k3-image-gen
  • modified Linux device tree
    &main_gpio0 {
        status = "reserved";
};

The example starts, but it required reserving whole main_gpio0 node.

The question is: is it possible to set reserved status only for one (or a few) GPIOs instead of a whole node?

First thing that came to my mind was gpio_reserved_ranges, but it seems like this value is ignored in the driver, also this particular parameter is not listed in the driver documentation (gpio_davinci.yml).

  • 0
    TI__Mastermind 44926 points

    Hi Mateusz,

    Thanks for the query.

    Please allow me sometime to get back to you.

    Regards,

    Vaibhav

  • 0
    TI__Guru**** 168211 points

    Hi Mateusz,

    It is not clear how your system partitions between Linux and FreeRTOS, but

    Mateusz Szalkowski said:
    The question is: is it possible to set reserved status only for one (or a few) GPIOs instead of a whole node?

    No, Linux doesn't support reserving a subset of GPIO pins.

  • 0 in reply to Bin Liu
    Prodigy 130 points

    Hi Bin,

    Thanks for the reply.

    For now the whole system is Yocto Linux running on one of the A53 cores and the GPIO interrupt example running on r5f0_0 (remoteproc starting from Linux). Booting the board using u-boot i.e. tiboot3.bin, tispl.bin and u-boot.img.

    Reserving a whole GPIO bank is a little drastic, also in the future one of those GPIOs might be needed for Linux purposes. If reserving a subset of GPIOs is not an option, is it possible to split the main_gpio0 into smaller (with 16 or 32 GPIOs) nodes?

    I tried to make some modifications in device tree to split the main_gpio0 to 2 separate banks e.g. main_gpio0 and main_gpio0a, one with 48 and second with 39 GPIOs, and remap GPIOs higher than 48 to main_gpioa (such as AM64x-SK onboard green heartbeat diode), but couldn't get GPIOs from second bank to work.

    Is there any workaround other than reserving the main_gpio0 node, or is it only solution?

    Regards,
    Mateusz

  • +1 in reply to Mateusz Szalkowski
    TI__Guru**** 168211 points

    Hi Mateusz,

    Regardless how main_gpio0 GPIO pins are partitioned, they are all under the single GPIO controller - main_gpio0, which can only be controlled in one OS. None of Linux on A53 or RTOS on R5F supports routing a portion of the GPIO pins to another remote CPU (A53 or R5F).

    So I don't see any workaround/solution, other than designing your board to only use a particular GPIO bank to a OS as an whole unit.

  • 0 in reply to Bin Liu
    Prodigy 130 points

    Hi Bin,

    Thank you for clearing that. I think that closes the discussion.

    Regards,
    Mateusz